This patent relates to a tubular corner post of the type used to cushion and protect a packaged article, such as a desk or appliance. More particularly, this patent relates to a tubular laminated paper corner post that has a variable cross-sectional profile along its height to accommodate irregularities in the shape of the packaged article.
Conventional corner posts are made by applying adhesive to paper, winding the wet paper around a mandrel and cutting the wound paper to a desired length to form one or more cylindrical tubes having a substantially circular cross-section, sliding the wound paper tubes onto a forming tool while the tubes are still malleable, forming the tubes into a desired shape, and allowing the adhesive between the paper layers to set up to form the finished tubes. Although conventional tubular corner posts may be cut to any length, they all have a uniform cross-sectional profile.
Many examples of conventional laminated corner posts are known in the art. For example, Gardner U.S. Pat. No. 4,482,054 discloses a laminated paper corner post having longitudinally-extending beads that provide improved resistance to longitudinally directed compression forces and enhanced cushioning against laterally directed forces. The corner post has a constant cross-sectional profile.
Gardner U.S. Pat. No. 4,483,444 discloses a corner post having a cross-sectional profile that accommodates overhang of the post relative to a bottom board without substantially reducing the resistance of the post to compressive forces. The cross-sectional profile is constant along the height of the post.
Hughes U.S. Pat. No. 5,267,651 discloses a corner post having laterally directed stiffening beads extending at an acute angle into free engagement with the opposite wall. When subjected to sufficient lateral force, the beads collapse onto themselves, forming intermediate layers between the inner and outer walls.
Qiu et al. U.S. Pat. No. 6,186,329 discloses a laminated corner post made from multiple sheets of paper. Like all the prior art corner posts described above, the Qiu corner post has a constant cross-sectional profile.
While each of these prior art corner posts is useful for its particular purpose, none has a variable cross-sectional profile to accommodate irregularities in the contours of the article being protected.
Thus it is an object of the present invention to provide a laminated paper corner post having a variable cross-sectional profile that can better accommodate the irregular contours of packaged articles.
Further and additional objects will appear from the detailed description, accompanying drawings, and appended claims.
The present invention is a new style of laminated paper corner post in which the cross-sectional profile varies along the length of the post. This variability improves the protective and cushioning properties of the post by allowing the post to mate better with certain features of the product being protected, such as trim lips, fragile contact points, protruding knobs, screw heads, etc.
Like conventional corner posts, the variable profile corner post is made by winding adhesive coated paper around a mandrel to form a cylindrical tube having a substantially circular cross-section, then sliding the still-wet tube onto a forming tool to form the desired shape. However, unlike conventional corner post manufacture, the forming tool has a variable cross-sectional profile, so that when the outer forming elements press the paper tube against the forming tool, the resulting corner post also has a variable cross-sectional profile.
In the preferred embodiment, the variable profile corner post has a lower section having a constant cross-sectional profile, an upper section having a different cross-sectional profile, and a middle section interposed between the first and second sections where the post transitions from one cross-sectional profile to the other cross-sectional profile. Because the variable profile corner post starts out as a cylindrical tube having a constant cross-section, the finished variable profile corner post has a constant circumference along its length.